Quick bulb-change electric lamp



Jan. 25, 1955 J. R. BASSLER QUICKBULB-CHANGE ELECTRIC LAMP Filed Nov. 15, 1952 IN V EN TOR.

Q a my WWW-B life 257g United States Patent QUICK BULB-CHANGE ELECTRIC LAMP John Robert Bassler, Newark, N. 3., assignor to Hudson Lamp Company, Arlington, N. J., a corporation of New Jersey Application November 15, 1952, Serial No. 320,769

2 Claims. (Cl. 2408.2)

The invention relates in general to electric lighting fixtures and has particular reference to lamps of the compact, weatherproof type that are commonly mounted on the bodies of large vehicles such as buses, vans and trailers for display of clearance lights to enable passing motorists to gauge safe clearance at night or under conditions of poor visibility in daytime.

Prior to my invention, the replacement of burned out light bulbs in lamps of this type has required dismantling of the lamp housing in each instance, the reason being that the bulb sockets used therein are of the conventional type that are open at one end only. Consequently, the housing must be opened suificiently to permit insertion of thumb and fingers into the interior far enough to grasp and rotate the bulb in the act of withdrawal or installation. The parts of the housing that must be removed to permit such finger access usually are held in place by two or more small screws which have to be operated by a screwdriver. Therefore, when one of the clearance lights on a vehicle burns out on the road, replacement of the defective bulb is certain to cause the driver considerable inconvenience and loss of time, especially under adverse weather conditions. Moreover, when it is raining or snowing, the exposed interior surfaces of the housing and bulb socket will become wet and thus subjected to the danger of short-circuiting.

With the above-mentioned disadvantages of the prior art lamps in mind, it has been my primary object to provide an improved lamp in which the bulb socket is of such construction that removal of a defective bulb and installation of a replacement bulb may be effected through an access opening in the housing wall that is just large enough for easy lengthwise passage of the bulb. The novel bulb socket, which will bedescribed in detail later herein, permits electrical connection of the base of a standard incandescent light bulb of the bayonet contact type therewith and disconnection therefrom without rotation and also permits bulb-first introduction of a replacement bulb. Consequently, a fresh bulb may be pressed into the socket through the housing access opening by one fingertip alone. Furthermore, the access opening is preferably located in the bottom wall of the housing so that a defective bulb will gravitate through said opening when released. It is thus practicable to close the substantially bulb-size access opening by means of a screw-plug closure having an external knurled head that may be manipulated easily without use of a screwdriver.

A further object of the invention is to provide a novel construction of the closure for the housing access opening whereby said closure serves to center and guide a replacement bulb during installation and also to create a highly efficient ground return connection between bulb and lamp housing.

An important advantage gained by the improved lamp structure is substantial reduction in size. By not having to allow for finger space inside the housing, the internal dimensions of the latter need be only slightly greater than the external size of the light bulb.

The above and other objects, features and advantages of the invention will be more fully understood from the following specific description when considered in connection with the accompanying illustrative drawing, in which:

Fig. 1 is a small scale fragmentary elevational view of one upper corner of a van body, showing clearance lamps of the improved construction mounted thereon in customary positions.

2,700,726 Patented Jan. 25, 1955 Fig. 2 is a detail front elevation on a larger scale of one of the lamps; Fig. 3 is a horizontal cross section on line 3-3 of Fig. 2, showing the lamp housing affixed to a fragmentary section of a vehicle body wall; Fig. 4 is a vertical section on line 44 of Fig. 2; Fig. 5 is an exploded view similar to Fig. 4, showing the closure plug and light bulb in detached positions aligned with the housing access opening; and Fig. 6 is a large scale crosssectional view on line 66 of Fig. 5 to show the specific structural details of the bulb socket.

Referring now in detail to the drawing, wherein like reference characters designate corresponding parts in the several views, Fig. 1 illustrates a pair of clearance lamps L embodying the present invention mounted in the usual I positions on the body of a vehicle V.

While the novel features of the invention have been embodied in a clearance lamp for the purpose of illustration, 'it is to be understood that it is within the scope of the invention to incorporate them in the construction of various other lamps of the same general type, such as those used for running lights on marine vessels and aircraft, for boundary and obstacle marker lights on airdromes, and for entrance lights and interior wall lights of buildings.

At this point, it may be stated by way of definition that the term light bulb or bulb is to be understood to mean a standard incandescent lamp comprising the usual plug-type socket-engaging base having insulated peripheral shell and central tip contacts, an evacuated glass bulb proper affixed to the end of the base opposite to the tip contact, and a light emitting filament sealed in the said bulb in electrical connection between said contacts. While a light bulb with a screw-type base or one with a bulb proper that is larger in diameter than the base are embraced by this definition, the particular light bulb which has been chosen as being best suited for use in the improved lamp is of the bayonet base contact type and one whose bulb proper is no larger in diameter than the base shell which bears the diametrically opposed bayonet contact lugs. Furthermore, the terms conductor or conducting material, are intended to refer to metallic elements possessing the property of conduction of elec tricity. On the other hand, the term insulator or insulating material is to be understood to mean rubber or some other material that is not a conductor of electricity.

Turning now to Figs. 2 to 6, which disclose the details of construction of one of the clearance lamps L on a larger scale than in Fig. 1, it will be observed that this lamp has a housing 10 which from general appearance is of well known type and construction. In fact, there is the usual armored body 11, which is made of heavy gauge steel and shaped to deflect any obstruction to traflic with which it may have grazing contact. Body 11 is adapted as usual to be attached by bolts 12 to wall v of the supporting vehicle body V. Standard hollow, semi-cylindrical lens 13 of appropriate color is detachably secured between top and bottom walls 14 and 15, respectively, of standard body 11 in the usual manner by guard 16, which latter is clipped to lens 13 as at 17 in order that a single set of screws 18 applied to said guard is the only means required to attach these two elements 13 and 16 to back wall 19 of body 11. By being clipped together, lens 13 and guard will remain intact while detached from body 11. A gasket 20 is interposed between the inner edges of lens 13 and back wall 19 of body 11 to seal the interior of housing 10 against entrance of moisture or dust. Gasket 20 usually is made of cork, which has insulating properties, so the gasket serves an additional purpose which will be explained later herein.

Back wall 19 of body 11 has an aperture 21 to admit the electrical lead from the positive side of the lighting circuit of the vehicle on which the lamp is mounted to supply electric current to the light bulb of said lamp. In accordance with standard practice, the metallic components of the body and frame of a motor vehicle are utilized for a ground return, so that is the reason for bolting the metallic body of lamp housing 10 directly to the metallic wall v of vehicle body V in the present instance.

Up to this point in the disclosure, all structural details of the clearance lamp L which have been above enumerated are known to the art. The novel features of the lamp will now be described.

The bulb socket of the old structure, to which access had to be gained by removal of the lens-guard unit 13716 from attachment to body 11, has been replaced in the improved lamp by an annular bulb socket 23 that opens axially in both directions instead of being closed at one end; Socket 23 is supported above bottom wall 15 of body 11 in close proximity thereto by an insulator 24 which has a circular bore 24" disposed in alignment with said socket but having a slightly large! diameter. A preferably circular access opening 25 is provided in bottom wall 15' in axial alignment withbore 24' of insulator 2 4 and with socket 23. The diameter of access opening 25 and that of insulator bore 24" are substantially equal and just large enough to afford sufiicient clearance for complete endwise penetration by astandard light. bulb B of I the bayonet base contact type illustrated in Figs. 3, 4- and 5 In other words, access opening 25 and insulator bore 24' will permit passage therethrough of bayonet contact lugs c of bulb B as well as base shell s and bulb proper b. However, socket 23 is of smaller diameter than access opening 25 and insulator bore 24 and will block passage of contact lugs c after upward bulb-first penetration of bulb proper b and base shell s. Consequently, an inse'rted light bulb B will be seated in socket 23 by abutment of contact lugs 0 against said socket, which abutment willbalso establish electrical contact between socket and bul Fig. 6 illustrates in greater detail the preferred structure of bulb socket 23 and insulator 24 as well as the precise mode of attachment of these parts to each other and to bottom wall 15 of body 11. Insulator 24 is composed of upper and lower laminae 26 and 27, respectively, which are secured suitably, as by rivets 28, to said bottom wall 15. Socket 23 is in the form of a plain flat ring susceptible of being stamped from a sheet metal blank and has at least two preferably diametrically opposed marginal cars 29 that pierce upperlarnina 26 of insulator 24 and are clinched against the underside of said upper lamina to secure the socket against dislodgment by upward thrust of bayonet contact lugs c of lamp B, such as might other wise occur when a replacement lamp is pushed into place in the socket with excessive pressure. As shown clearly in Fig. 3, cars 29 are spaced from rivets 28 sufiiciently to prevent any short-circuiting electrical contact therebetween. Moreover, short-circuiting contact between socket 23 and back wall 19 of body 11 will be prevented by interposed gasket 20, which explains the use of insulating material in its manufacture. Figs. 3 and 6 disclose a solder connection, binding screw or the like 30 by which electricallead 22 is connected to socket 23.

Access opening 25 in bottom wall 15 of body 11 is closed by a removable closure, which preferably is in the form of a plug 31 of circular cross section made of conducting material and having screwthreaded engagement with said opening. This closure plug 31 is of such large diameter as compared to fastening screws 18 that it is practicable to provide its outer end with a knurled manipulating head 32, thereby eliminating the use of a screwdriver. To seal the joint between manipulating head 32 and bottom wall 15 of the body 11 against entrance of dust and moisture, a washer 33 may be interposed. An important function of closure plug 31 is to effect a ground connection between central tip contact t of light bulb l?- and body 11 when said closure plug is in closed position in relation to access opening 25. While this connection may be effected by direct contact between the inner end of closure plug 31 and tip contact t of bulb B. it is preferred to intcrpose a yielding spring contact member 34 between said plugand tip contact. The best results are obtained by making spring contact member 34 in the form of a frusto-conical helical coil and by seating the larger end thereof in a countersink 35 provided in the upper end of closure plug 31. The smaller end of contact member 3 which will face upwardly, should be large enough in diameter to contactingly embrace tip contact t of bulb B below its area of maximum diameter. As a result, spring contact member 34 will perform several useful functions. in addition to making electrical contact between bulb tip contact r and closure plug 31, it will accurately center the base end of bulb B to preventwobbling and possible binding when the bulb is being forced into socket 23. Moreover, it will press bayonet contact lugs c firmly and evenly against diametrically opposite sides of socket 23 to promote the efficiency of the electrical connection. Then, too, when closure plug 31 is screwed up tight, the upper end convolution of spring contact member 34 will be expanded by wedging action of tapered tip contact I of bulb B. Besides affording increased area of electrical contact, which is an important advantage, there will be consequent abrasion of the contacting surfaces to promote a better electrical connection.

The manner in which the improved, lamp facilitates quick replacement of burned out light bulbs will be, understood most clearly by referring to Figs. 4 and 5. When a bulb B that is engaged with socket 23 of the lamp (Fig. 4) requires replacement, closure plug 31 is simply unscrewed and removed carefully from access opening 25 to permit the released bulb to fall into the hand that is manipulating the plug. Then, the replacement bulb is inserted bulb-first with the other hand into access opens 25 and u e p us '1 s reapp ied. nd s ew d p tight. Instead of pushing the bulb completely home with a fingertip, it may be partially inserted in access opening 25 and then the upper end convolution of spring contact member 34 may be cupped against tip contact t of the bulb. With the bulb thus firmly supported and centered in opening 25, closure plug 31 will guide thejbulb straight and forcefully into socket 23 as it is screwed into place,

It should now be apparent that my invention renders replacement of clearance lamps an extremely simple and convenient operation even under adverse weather and other conditions and requires only a brief moment for accomplishment. Moreov r, it is prafitically impossible for rain or snow to enter the lamp housing through access opening 25, due to its VQIY Small size and, tofits pro: tected location underneath the housing.

It will be understood that it is intended to. cover all changes and modifications of the examples of the invention, herein chosen for the purpose of illustration which do not constitute departures from the spirit and scope thereof.

Having thus described the invention, I claim;

1. A lighting fixture for clearance signal service in connection with automotivevehicles andfor other uses comprising a hollow metallic body formed by back, top and bottom walls and having a light emission front lens supported thereby, the bottom wall of said housing body having an internally screw-threaded access opening to admit upward insertion into the housing body interior of an electric lamp bulb of the standard bayonet base contact type, an insulator member afiixed upon the inner face of the bottom wall of the housing body, said insulator member having a'through opening disposed in axial alignment with said accessopening and being of diametric size large enough to pass the bayonet contact lugs of the base of an inserted lamp bulb, a metallic contact socket ring supported by said insulator member, the opening of said socket ring being disposed in axial alignment with the opening of said insulator member and being of diameter largeenough to pass the inserted lamp bulb and its base but smaller in diameter thanthe diametric distance between the tips of the bayonet contact lugs of said base, whereby to provide a shoulder against which said bayonet contact lugs abut so as to make electrical connection with the, socket ring,means to connect the socket ring in anelectric circuit which ineludes the housing body as a ground, a removable metallic screwsthreaded plug to close SZIid'flCCQSS opening of the housing body, and saidplug having compression spring means to both-electricallyground the central tip contact of the base of the inserted lamp bulb and hold the bayonet contact lugs thereof in electrical contact with said socket ring, the inserted lamp bulb being adapted to drop by gravity out of thehousing body when said closure plug is detached from the latter.

2. A lighting fixture accordingto claim 1, wherein the closure plug is provided with. acountersunk cavity in its inner end, and the compression spring means comprises a frusto-conical helical coil seated in said cavity with its smaller end adapted to tensionally and contactingly engage the centraltip contact-of the base of the inserted lamp bulb.

2,473,479 Suwa June 14, 1949 

